Catalyst component for use in the polymerization of α-olefins and a method of using the same

ABSTRACT

A supported titanium catalyst is produced by cogrinding, in combination, a magnesium halide, tetravalent titanium halide, organic acid ester, and an organic halogen compound. The resulting supported titanium catalyst, when employed as a titanium component with an organo aluminum catalyst component for the catalyst system in a process for stereoregular polymerization of α-olefins, produces high polymerization activity and unexpectedly high stereoregular polymer yielding ratios.

This is a division of application Ser. No. 29,083, filed Apr. 11, 1979,now U.S. Pat. No. 4,242,231.

BACKGROUND OF THE INVENTION

This invention relates to a catalyst component for use in thepolymerization of α-olefins and to a process for the polymerization ofα-olefins using the same, and more particularly, it is concerned with asupported titanium catalyst component prepared by an improved processand with a process for producing a stereoregular homopolymer orcopolymer of α-olefins using a catalyst system comprising the supportedtitanium catalyst component and an organo aluminum catalyst component.

For the stereoregular polymerization of α-olefins, it has hitherto beencarried out to use a catalyst system comprising solid TiCl₃, obtained byreducing TiCl₄ by various methods, and an organo aluminum compound ascocatalyst. However, this method has many disadvantages on a commercialscale in that both the polymerization activity and stereoregularity ofcommercially available catalyst systems are low and steps for polymerdeashing and for removing amorphous polymers are required. In order toovercome these disadvantages, there have been proposed processes for thepolymerization of α-olefins by the use of catalyst systems comprising,by way of example, titanium catalyst components obtained by treatingsolids, obtained by reducing TiCl₄ with organo aluminum compounds, withcomplexing agents and then with TiCl₄ (Japanese Pat. No. 3356/1978) orby treating the solids with complexing agents and hexachloroethane(Japanese Patent Public Disclosure No. 107294/1977). In these examples,as far as solid TiCl₃ is used, however, only a part of the titanium canbe utilized as active catalyst and, consequently, there is not obtainedsuch a high catalytic efficiency as to omit the deashing step.

As a desirable method for raising the polymerization activity per unittitanium, on the other hand, it has been known to disperse and supporttitanium compounds on other solids. Actually, in the production ofpolyethylene by middle or low pressure process, a high catalyticefficiency can be achieved by the use of a catalyst system comprising atitanium catalyst component (titanium compounds on various supports) andan organo aluminum compound component. A polymeric product of goodquality can be produced on a commercial scale without polymer deashingstep. However, in the polymerization of higher α-olefins, e.g.,propylene, a high polymerization activity as well as a highstereoregularity are required, resulting in a more difficult problemthan in the case of producing polyethylene by middle or low pressureprocess.

Of late, various improved methods have been proposed as to thestereoregular polymerization of α-olefins using a catalyst systemcomprising a supported titanium catalyst component and an organoaluminum catalyst component. For example, there are: (1) a methodcomprising using a catalyst system composed of a solid supportedtitanium catalyst component obtained by cogrinding an anhydrousmagnesium halide and titanium halide or complex of a titanium halide andan electron donating compound, and an organo aluminum catalyst componentconsisting of a trialkylaluminum and electron donor (Japanese PatentPublic Disclosure Nos. 16986-8/1973); (2) a method comprising using acatalyst system composed of a supported titanium catalyst componentobtained in a similar manner to set forth above except in the presenceof an organic solid such as durene, hexachlorobenzene or polyolefin andan inorganic solid such as lithium chloride, calcium chloride oralumina, which are substantially inert to the other compounds forcomposing the catalyst, and an organo aluminum catalyst componentconsisting of a trialkylaluminum and electron donating compound(Japanese Patent Public Disclosure No. 86482/1974); and (3) a methodcomprising using, in combination, a supported titanium catalystcomponent, obtained by contacting a magnesium alkoxide, titaniumtetrahalide, electron donating compound and halosilane, and an organoaluminum catalyst component consisting of an organo aluminum compoundand electron donating compound (Japanese Patent Public Disclosure No.98076/1977).

However, the stereoregularity of a polymer produced by the use of such acatalyst system is not always satisfactory and, in particular, whenusing a molecular weight regulator such as hydrogen, thestereoregularity is markedly lowered. Therefore, the prior art methodsare insufficient for fully omitting the step of removing amorphouspolymers.

SUMMARY OF THE INVENTION

The present invention provides a process whereby the stereoregularity ismainly improved. That is to say, in accordance with the presentinvention, there is provided a commercially available process for thepolymerization of α-olefins, in which homopolymerization of α-olefins orcopolymerization with ethylene or other α-olefins is carried out with anexcellent stereoregularity even in the presence of a molecular weightregulator such as hydrogen. The process is achieved by cogrinding and/orusing a catalyst system composed of a supported titanium catalystcomponent, obtained by cogrinding and/or contacting a magnesium halide,preferably, anhydrous magnesium dihalide, tetravalent titanium halideand organic acid ester in the presence of an organo halogen compound,preferably a halogen substituted hydrocarbon, and an organo aluminumcatalyst component consisting of an organo aluminum compound and organicacid ester.

DETAILED DESCRIPTION OF THE INVENTION

As the magnesium halide, in particular, anhydrous magnesium dihalide ofthe present invention, there are ordinarily used MgCl₂, MgBr₂ and MgI₂.Above all, MgCl₂ is preferable. These anhydrous magnesium dihalides maybe those synthesized by any methods and commercially sold compounds can,of course, be used. It is desirable that the magnesium dihalide issubstantially anhydrous and it is not always necessary to be completelyanhydrous. Preferably, a commercially sold anhydrous magnesium dihalide,prior to use thereof, is subjected to a dehydration treatment inconventional manner, for example, by firing (calcining, baking) at atemperature of 100° to 400° C. under reduced pressure for 1 to 10 hours,but the presence of water in such an extent that the catalyticperformance is not affected is allowed.

Typical examples of tetravalent titanium halides used in the presentinvention are TiCl₄, TiBr₄ and TiI₄. However, it is not always necessarythat all the anions of these titanium halides are halogens, but a partthereof can be substituted by alkoxy, acyloxy or alkyl groups. Ofcourse, TiCl₄ is preferred for catalyst components for use instereoregular (co)polymerization of higher α-olefins, e.g., propylene.

The organic acid esters used in the present invention are esters ofsaturated or unsaturated aliphatic, alicyclic and aromatic mono- orpolycarboxylic acids and aliphatic, alicyclic and araliphatic mono- orpolyols. Examples of these esters are butyl formate, ethyl acetate,butyl acetate, ethyl acrylate, ethyl butyrate, isobutyl isobutyrate,methyl methacrylate, diethyl maleate, diethyl tartrate, ethylhexahydrobenzoate, ethyl benzoate, ethyl p-methoxybenzoate, methylp-methylbenzoate, ethyl p-tert-butylbenzoate, dibutyl phthalate, diallylphthalate and ethyl α-naphthoate. The organic acid esters of the presentinvention are not intended to be limited to these examples. Above all,alkyl esters of aromatic carboxylic acids, in particular, C₁ to C₈ alkylesters of benzoic acid or derivatives thereof are preferably used.

Typical examples of the organic halogen compound which may be used inthe present invention are halogen-substituted hydrocarbons, i.e., mono-and polyhalo substituted products of saturated or unsaturated aliphatic,alicyclic and aromatic hydrocarbons having 1 to 20 carbon atoms. Forexample, the aliphatic compounds are methyl chloride, methyl bromide,methyl iodide, methylene chloride, methylene bromide, methylene iodide,chloroform, bromoform, iodoform, carbon tetrachloride, carbontetrabromide, carbon tetraiodide, ethyl chloride, ethyl bromide, ethyliodide, 1,2-dichloroethane, 1,2-dibromoethane, 1,2-diiodoethane,methylchloroform, methylbromoform, methyliodoform,1,1,2-trichloroethylene, 1,1,2-tribromoethylene,1,1,2,2-tetrachloroethylene, pentachloroethane, hexachloroethane,hexabromoethane, n-propyl chloride, 1,2-dichloropropane,hexachloropropylene, octachloropropane, decabromobutane and chlorinatedparaffins. The alicyclic compounds are chlorocyclopropane,tetrachlorocyclopentane, hexachloropentadiene and hexachlorocyclohexane.The aromatic compounds are chlorobenzene, bromobenzene,o-dichlorobenzene, p-dichlorobenzene, hexachlorobenzene,benzotrichloride and p-chlorobenzotrichloride. The present invention isnot intended to be limited thereby. In addition to these halosubstituted oxygen-containing compounds, for example, hexachloroacetone,chloroacetic acid esters, trichloroacetic acid esters and the like.

Above all, however, polyhalo substituted hydrocarbons, in particular,polychloro substituted products of aliphatic hydrocarbons having 1 to 4carbon atoms are preferably used and most preferably, carbontetrachloride, 1,1,2-trichloroethylene, 1,1,2,2-tetrachloroethane,hexachloroethane and octachloropropane are used. As exemplifiedhereafter, hexachloroethane has provided the most consistent superiorresults.

The supported titanium catalyst component of the present invention isobtained by subjecting (a) anhydrous magnesium dihalide, (b) tetravalenttitanium halide, (c) organic acid ester and (d) organo halogen compoundto a cogrinding and/or contacting treatment by various manners. That is,in the production thereof, the adding methods and contacting orders ofthese compounds can be suitably varied, but it is required that all ofthese compounds are finally brought into contact with each other. Thecogrinding and/or contacting treatment is preferably carried out as tothe following systems each consisting of a combination of thesecompounds and, particularly preferably, is carried out by mechanicalgrinding using a vibrating mill, ball mill, etc:

(i) mixtures of (a), (b), (c) and (d);

(ii) mixtures of (b), (d) and a complex (e) formed previously from (a)and (c);

(iii) mixtures of (a), (d) and a complex (f) formed previously from (b)and (c);

(iv) mixtures of (b), (c) and a complex (g) formed previously from (a)and (d);

(v) mixtures of (f) and (g);

(vi) mixtures of (e), (f) and (d);

(vii) mixtures of (a), (f) and (d); and

(viii) mixtures of (d) and a complex (h) formed previously from (a) and(f).

Above all, a method for forming previously a complex is preferablyselected from wet process or dry process mechanical grinding treatmentsand contacting treatments in the presence or absence of a solvent atroom temperature or with heating, and each of the mixtures can beprepared by mixing the components at a time or in order.

In the present invention, it is necessary to effect grinding until thereis produced a change of intensity in the peaks of 14.8° (strong) and30.2° (middle) of the characteristic peaks (20) in the X-ray diffraction(45 KV×45 mA, CuK.sub.α source, Ni filter) of anhydrous magnesiumchloride used as a support, although the mechanical grinding efficiencydepends on the grinding system, the structure of a grinding apparatus,the quantity of starting materials charged, voids, temperature, etc.More preferably, the grinding is carried out in such an extent that thepeak of 14.8° becomes dull with an increased width and the other peak of30.2° loses its intensity to a great extent. In the case of charging 10to 50 g of a mixture in a vibration mill of 300 ml in inner volume,having 100 steel balls of 10 m/m in diameter, and grinding at avibration width of 1 to 3 m/m and a vibration number of 1400 vpm, forexample, the grinding time is usually 1 to 200 hours, preferably 10 to100 hours.

The quantity of a titanium halide on a support is preferably 0.1 to 10%by weight as titanium metal. An organic acid ester is preferably used ina proportion of 0.1 to 10 mols, particularly, 0.5 to 5 mols to 1 gramatom of the supported titanium metal and an organo halogen compound ispreferably used in a proportion of 1 to 100% by weight, particularly, 5to 50% by weight to the anhydrous magnesium halide.

It is surprisingly found that according to the above-described method, acomplex composed of (a), (b), (c) and (d) can be obtained in a flowablesolid form even if an organo halogen compound used is liquid.

The supported titanium catalyst component obtained in this way has asubstantially similar surface area and pore volume to one prepared inthe absence of an organo halogen compound. However, when using thesupported titanium catalyst component of the present invention incombination with an organo aluminum catalyst component, it is capable ofimparting a high stereoregularity with keeping a high polymerizationactivity in the homopolymerization of α-olefins or copolymerization withethylene or other α-olefins.

As an organo aluminum compound for the abovedescribed organo aluminumcatalyst component there is used ordinarily an organo aluminum compoundrepresented by the general formula R_(m) AlX_(3-m), wherein R representsan alkyl group or aryl group having 1 to 18 carbon atoms, X represents ahalogen anion and m represents a suitable numeral within a range of2<m≦3, or a mixture or a complex compound thereof. For example,trialkylaluminums are used. There are preferably used as an organoaluminum compound to be used jointly with the trialkylaluminums,alkylaluminum compounds having 1 to 18 carbon atoms, in particular, 2 to6 carbon atoms, such as dialkylaluminum monohalides, monoalkylaluminumdihalides and alkylaluminum sesquichlorides, or mixtures or complexcompounds thereof. Examples of preferred trialkylaluminums aretrimethylaluminum, triethylaluminum, tripropylaluminum andtriisobutylaluminum. Examples of preferred dialkylaluminum monohalidesare dimethylaluminum chloride, diethylaluminum chloride, diethylaluminumbromide, diethylaluminum iodide and diisobutylaluminum chloride.Examples of preferred monoalkylaluminum dihalides are methylaluminumdichloride, ethylaluminum dichloride, ethylaluminum dibromide,ethylaluminum diiodide and butylaluminum dichloride. An example of apreferred alkylaluminum sesquihalide is ethylaluminum sesquichloride. Inparticular, it is preferable to use triethylaluminum,triisobutylaluminum and as one to be used jointly with them,diethylaluminum chloride and ethylaluminum sesquichloride, or mixturesor complex compounds thereof, because these compounds are readilyobtainable commercially and exhibit excellent effects.

When the above-described organo aluminum compound only is used with thesupported titanium catalyst component for the polymerization ofα-olefins in the presence of a molecular weight regulator such ashydrogen, however, the yield of a stereoregular polymer is remarkablydecreased. This is disadvantageous commercially. Therefore, theabove-described organo aluminum compound and an organic acid ester, incombination, are preferably used as the organo aluminum catalystcomponent of the present invention. A suitable organic acid ester may besame as or different from used for the preparation of the supportedtitanium catalyst component described above and their ratio is chosenwithin a range of 0.1 to 10 gram atoms, preferably 1 to 5 gram atoms ofaluminum in the organo aluminum compound to 1 mol of the organic acidester.

Preparation of such an organo aluminum catalyst component is carried outby contacting an organo aluminum compound and organic acid ester, forexample, by merely mixing them at room temperature or while using asuitable hydrocarbon, such as n-hexane or n-heptane, as a diluent. Theorgano aluminum catalyst component is ordinarily prepared before apolymerization reaction, but, in general, it is preferably used within 1hour after the component is prepared since the stereoregularity isunfavorable affected if it is used after storage of the complex for along time.

The catalyst system of the present invention can be used for thepolymerization of α-olefins, in particular, for the stereospecificpolymerization of α-olefins having 3 to 6 carbon atoms, for example,propylene, butene-1, 4-methylpentene-1 and hexene-1 and for thecopolymerization of α-olefins with each other and/or with ethylene. Thiscopolymerization includes random copolymerization and blockcopolymerization. In the case of using ethylene as a comonomer, itsproportion is generally chosen within a range of up to 30% by weight, inparticular, 1 to 15% by weight to α-olefins. A polymerization reactionusing the catalyst system of the present invention is carried out underordinary conventional polymerization conditions. The reaction is carriedout in any of a gaseous phase and liquid phase, and for the reaction ofliquid phase, any of inert hydrocarbons and liquid monomers can be used.A suitable solvent for the polymerization is selected from the foregoinghydrocarbons. The polymerization temperature is generally -80° C. to150° C., preferably 40° to 100° C. The pressure ranges, for example, 1to 40 atm. Control of the molecular weight during polymerization iscarried out in conventional manner using hydrogen or another knownmolecular weight regulator.

The polymerization can be carried out continuously or batchwise. Theorgano aluminum catalyst component is, of course, utilized for thepolymerization reaction and further serves to catch various catalystpoisons introduced into the system. Thus, it is necessary to control theadditive quantity of the organo aluminum catalyst component consideringthe quantities of catalyst poisons contained in α-olefins, solvents orvarious gases, in particular, when using a high activity catalyst as inthe present invention, and, ordinarily, the organo aluminum catalystcomponent is used so as to satisfy an Al/Ti atomic ratio of 1 to 2000,preferably 50 to 1000, based on titanium in the supported titaniumcatalyst component.

When polymerization is carried out according to the process of thepresent invention, the stereo-regularity can largely be improved whileholding a high polymerization activity and, consequently, the steps ofremoving the catalyst (deashing) and removing atactic polymers becomeunnecessary or the load thereon is markedly reduced. The process of thepresent invention is particularly important for the production ofisotactic polypropylene, random copolymers of ethylene and propylene andblock copolymers of propylene and ethylene.

The present invention will now be illustrated in detail by the followingexamples. However, the present invention is not intended to be limitedthereby without departing from the spirit of the present invention. Inthese examples, percents are to be taken as those by weight unlessotherwise indicated. The polymerization activity or catalyst efficiency(which will hereinafter be referred to as "C.E.") is the quantity (g) ofa polymer formed per 1 g of titanium in the catalyst. Theheptane-insoluble component (which will hereinafter be referred to as"H.I.") to show the proportion of a crystalline polymer in the polymersmeans the residual quantity (% by weight) in the case of extracting thepolymer product with boiling n-heptane for 6 hours by means of a Soxhletextractor of an improved type. The melt flow rate (which willhereinafter be referred to as "M.F.R.") is measured according to ASTM-D1238.

EXAMPLE 1 Preparation of Titanium Catalyst Component

28.7 g (64%) of anhydrous magnesium chloride, 7.7 g (17%) of anequimolar complex of titanium tetrachloride and ethyl benzoate (whichwill hereinafter be referred to as "E.B."), i.e., TiCl₄.C₆ H₅ CO₂ C₂ H₅,and 8.5 g (19%) of hexachloroethane were charged in a stainless steel(SUS 32) mill pot with an inner volume of 300 ml carrying 100 stainlesssteel (SUS 32) balls with a diameter of 10 mm in a nitrogen atmosphere,which was then fitted to a shaker, followed by shaking for 20 hours tocontact them. The thus obtained titanium-containing solid was yellow andhad a composition of 16.3% Mg, 74.7% Cl, 6.8% E.B. and 2.2% Ti. Thesurface area of the solid measured by the BET method was 5.2 m² /g andthe pore volume was 0.016 cc/g. The results of X-ray diffration (45KV×45 mA, CuK.sub.α source, Ni filter) of the solid showed that thepeaks of 14.8° and 34.8° of the characteristic peaks of anhydrousmagnesium chloride became dull with an increased width, the peaks of30.2° and 63° disappeared and the peak of 50.3° was not changed.

EXAMPLE 1 Polymerization (A)

35.1 mg of the above-described titanium catalyst component (Ti supportratio: 2.2%) was charged in a stainless steel (SUS 32) autoclave with aninner volume of 1000 ml, equipped with a stirrer, in a nitrogenatmosphere. Then, a solution of 1 mol/l of triethylaluminum in n-heptanecorresponding to an Al/Ti molar ratio of 300 and E.B. corresponding toan Al/E.B. molar ratio of 3.4 were previously mixed, held for 3 minutesand added thereto. Furthermore, 0.6 l of hydrogen gas as a molecularweight regulator and 0.8 l of liquid propylene were forceably introducedunder pressure and the system was heated at 68° C. to effectpolymerization for 30 minutes. After the polymerization, the unreactedpropylene was purged and 94 g of a white powdered polypropylene wasobtained. The results of catalyst performance, pressured per above,were: a C.E. of PP 123,000 g/g-Ti; H.I.=90.1%; M.F.R.=2.5.

EXAMPLE 1 Polymerization (B)

A second polymerization was carried out in an analogous manner toPolymerization (A) of Example 1 except 46.5 mg of the titanium catalystcomponent was used and triisobutylaluminum was used in place of thetriethylaluminum, thus obtaining 116.3 g of polypropylene having a H.I.of 89.6%. C.E. was PP 114,000 g/g-Ti.

COMPARATIVE EXAMPLE 1

The procedure of Example 1 was repeated except using 40.3 g of anhydrousmagnesium chloride, 11.1 g of the complex TiCl₄.C₆ H₅ CO₂ C₂ H₅ and nohexachloroethane. The thus resulting titanium-containing solid wasyellow and had a composition of 20.5% Mg, 68.2% Cl, 8.4% E.B. and 2.9%Ti. The specific surface area of the solid measured by the BET methodwas 10.8 m² /g and the pore volume was 0.032. The results of X-raydiffraction showed that the peaks of 14.8° (strong) and 50.3° of thecharacteristic peaks of anhydrous magnesium chloride became dull with anincreased width and the peaks of 30.2° (middle), 34.8° (weak) and 63°(weak) disappeared. The different point from Example 1 consists in thatthe peak of 34.8° disappeared.

COMPARATIVE EXAMPLE 1 Polymerization (A)

Polymerization was carried out in an analogous manner to Example 1,Polymerization (A), except using 36.1 mg of the above-described titaniumcatalyst component, thus obtaining 121 g of powdered polypropylene.Polymerization results were a C.E. of PP 115,000 g/g-Ti and a H.I. of86.5%.

COMPARATIVE EXAMPLE 1 Polymerization (B)

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using 33.5 mg of the above-described titaniumcatalyst component, thus obtaining 91.4 g of polypropylene.Polymerization results were a C.E. of PP 94,000 g/g-Ti and a H.I. of86.0%.

EXAMPLE 2

23.7 g (60.8%) of anhydrous magnesium chloride, 8.3 g (21.3%) of thecomplex TiCl₄.C₆ H₅ CO₂ C₂ H₅ and 7.0 g (17.9%) of hexachloroethane werecharged in the same vibration mill as used in Example 1 and ground for44 hours to obtain a yellow solid having a Ti content of 2.5%.

EXAMPLE 2 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent, thus obtaining polypropylene polymerization results of a C.E.of PP 157,000 g/g-Ti and a H.I. of 91.2%. In comparison with ComparativeExample 1, both of C.E. and H.I., in particular, the latter is markedlyimproved.

EXAMPLE 3

The procedure of Example 2 was repeated except 22.2 g (62.0%) ofanhydrous magnesium chloride, and 8.3 g (23.2%) of the complex TiCl₄.C₆H₅ CO₂ C₂ H₅ were used and 5.3 g (14.8%) of carbon tetrachloride wasused in place of hexachloroethane, thus obtaining a yellow green solidcontaining 2.7% of Ti.

EXAMPLE 3 Polymerization

Polymerization was carried out in a similar manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent. C.E.=PP 73,300 g/g-Ti, H.I.=90.2%.

EXAMPLE 4

The procedure of Example 3 was repeated except 1,1,2-trichloroethylenewas added in place of the carbon tetrachloride, thus obtaining a yellowgreen solid containing 3.6% of Ti.

EXAMPLE 4 Polymerization

A polymerization test was carried out in an analogous manner to Example1, Polymerization (B), except using the above-described titaniumcatalyst component. C.E.=PP 81,900 g/g-Ti, H.I.=93.7%.

EXAMPLE 5

The procedure of Example 3 was repeated except p-chlorobenzotrichloridewas added instead of the carbon tetrachloride, thus obtaining a greensolid containing 3.0% of Ti.

EXAMPLE 5 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent. C.E.=PP 43,700 g/g-Ti and H.I.=88.0%.

EXAMPLE 6

The procedure of Example 2 was repeated except 13.4 g (56.1%) ofanhydrous magnesium chloride and 4.1 g (17.2%) of the complex TiCl₄.C₆H₅ CO₂ C₂ H₅ were used and 6.4 g (26.8%) of hexachlorobenzene was usedin place of hexachloroethane, thus obtaining a yellow solid containing2.4% of Ti.

EXAMPLE 6 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent. The results obtained were: a C.E. of 98,000 g PP/g-Ti; and aH.I. of 87.8%.

EXAMPLE 7

The procedure of Example 1 was repeated except an equimolar complex oftitanium tetrachloride and ethyl p-methoxybenzoate was used in place ofthe equimolar complex of titanium tetrachloride and ethyl benzoate, thusobtaining a yellow solid containing 2.3% of Ti.

EXAMPLE 7 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent. The results obtained were: a C.E. of 103,000 g PP/g-Ti; and aH.I. of 91.1%.

EXAMPLE 8

The procedure of Example 2 was repeated except an equimolar complex oftitanium tetrachloride and isobutyl isobutyrate was used in place of theequimolar complex of titanium tetrachloride and ethyl benzoate, thusobtaining a yellow solid containing 2.5% of Ti.

EXAMPLE 8 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent, thus obtaining results of a C.E. of 83,000 g PP/g-Ti and aH.I. of 89.5%.

EXAMPLE 9

The procedure of Example 2 was repeated except the contacting orgrinding method was varied as follows: Firstly, the anhydrous magnesiumchloride and ethyl benzoate only were charged in a vibration mill andpreviously coground for 3 hours. Then, the hexachloroethane and titaniumtetrachloride were simultaneously added, followed by further cogrindingfor 42 hours, thus obtaining a yellow solid having a titanium content of2.1%.

EXAMPLE 9 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent, thus obtaining polymerization results of a C.E. of 98,000 gPP/g-Ti and a H.I. of 89.6%.

EXAMPLE 10

The procedure of Example 2 was repeated except the contacting orgrinding method was varied as follows: Firstly, the anhydrous magnesiumchloride and hexachloroethane were charged in a vibration mill andpreviously coground for 3 hours. Then a previously prepared equimolarcomplex of titanium tetrachloride and ethyl benzoate was further added,followed by cogrinding for 42 hours, thus obtaining a yellow solidhaving a titanium content of 2.2%.

EXAMPLE 10 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent, thus obtaining polymerization results of a C.E. of 115,000 gPP/g-Ti and a H.I. of 90.7%.

The effects on an organic acid ester in the organo aluminum catalystcomponent will be shown in the following:

EXAMPLE 11

A polymerization was carried out in a similar manner to the Example 2,Polymerization, except triethylaluminum and ethyl p-anisate were used inplace of the triisobutylaluminum and ethyl benzoate as the organoaluminum catalyst component of Example 2. The polymerization resultswere: C.E.=138,000 g PP/g-Ti; H.I.=90.3%.

EXAMPLE 12

A polymerization was carried out in an analogous manner to the Example2, Polymerization, except ethyl p-toluate was used in place of the ethylbenzoate as the organic acid ester in the organo aluminum component,thus obtaining polymerization results of a C.E. of 113,000 g PP/g-Ti anda H.I. of 89.8%.

Examples of random copolymers will be given as follows:

EXAMPLE 13

The procedure of Example 1, Polymerization (B), was repeated except 4.5g of ethylene gas was also added. The copolymerization results were:185,000 copolymer g/g-Ti; and H.I. 85.2%. The resulting copolymercontained 2.7% of ethylene and an M.F.R. of 2.3.

EXAMPLE 14

A cogrinding treatment was carried out in an analogous manner to Example2 except carbon tetrabromide was used in place of the hexachloroethane,thus obtaining a canary yellow flowable solid having a Ti content of3.1%.

EXAMPLE 14 Polymerization

Polymerization was carried out in an analogous manner to Example 1,Polymerization (B), except using the above-described titanium catalystcomponent, thus obtaining polymerization results of a C.E. of 142,000 gPP/g-Ti and a H.I. of 90.7%.

What we claim is:
 1. In a process for the stereoregular polymerizationof α-olefins, wherein an α-olefin is contacted, under α-olefin(co)polymerization conditions, with a catalyst system comprising atitanium catalyst component and an organo aluminum catalyst componentprepared by mixing an organo aluminum compound and an organic acidester, the improvement comprising:the titanium catalyst component beingobtained by co-grinding, in combination, a magnesium halide, atetravalent titanium halide in the amount of from about 0.1 to about 10percent by weight as supported titanium metal in the resultingtitanium-containing solid product, from about 0.1 to about 10 moles per1 gram atom of supported titanium metal of an organic acid ester and anorganohalogen compound in proportion of 1 to 100 percent by weight tothe magnesium halide, said organohalogen compound being one of mono- orpolyhalo-substituted saturated aliphatic or saturated alicyclichydrocarbons having from 1 to 20 carbon atoms.
 2. The process of claim 1wherein the halogen-substituted hydrocarbon is a polychloroaliphatichydrocarbon having from from 1 to 4 carbon atoms.
 3. The process ofclaim 1 wherein the magnesium halide is anhydrous magnesium dichloride,the tetravalent titanium halide is titanium tetrachloride, and the esteris selected from alkyl esters of aliphatic, alicyclic and aromaticcarboxylic acids.
 4. The process of claim 3 wherein the ester isselected from a C₁ -C₈ alkyl ester of benzoic acid or a derivativethereof.
 5. The process of claim 2 wherein the polychloro-substitutedhydrocarbon is hexachloroethane.